A guide wire may be used to route a component through a passageway to a location that may be otherwise relatively inaccessible. For example, a physician may use a guide wire to implant a cardiac lead in a patient's heart. Here, the guide wire may be initially inserted into a vein of the patient then routed through the vein to the heart. In some applications the lead may then be routed over the guide wire for implantation.
In general, a guide wire must be sufficiently rigid so that it may be pushed through a desired path yet be sufficiently flexible to enable it to navigate bends and obstacles in the path. In the example of a guide wire for implanting a cardiac lead, the guide wire must be sufficiently stiff to enable a physician to advance the guide wire through the vein (and potentially through tissue) by pushing on a proximal end of the guide wire. In addition, the guide wire needs to be sufficiently flexible to navigate various bends in the vein as the guide wire is directed toward the heart.